Reclamation history and land use types across multiple spatial scales shape anuran communities in the coastal land reclamation region

Land reclamation is a widely adopted method for managing land shortage and promoting coastal economic development globally. However, its impacts on biodiversity vary based on distinct reclamation histories and land use management strategies in different regions. This study aims to examine the effects of reclamation history and land use types at different spatial scales on anuran communities in coastal reclaimed land, which are an important taxon in the coastal ecosystem. We used visual and acoustic encounter methods to survey anurans in 2016 and 2017 across 20 1-km radius coastal land reclamation landscapes with different reclamation histories (10, 20, and 60 y after reclamation) in Nanhui Dongtan of Shanghai, an important coastal land reclamation region along the Yangtze River Estuary. Landscape variables (farmlands, woodlands, and impermeable surface covers, and the landscape Shannon diversity index) at four different spatial scales (250 m, 500 m, 750 m and 1000 m) and water salinity in each landscape were measured. Our findings reveal differences in anuran communities between study sites with 10, 20, and 60 years of reclamation history. Abundances of the ornamented pygmy frog (Microhyla fissipes) and Beijing gold-striped pond frog (Pelophylax plancyi) in landscapes with a 10-year reclamation history were significantly lower compared to those with histories of 20 and 60 years. Zhoushan toad (Bufo gargarizans) abundance was significantly negatively related to farmland cover at the 1000 m scale and impermeable surface cover at the 250 m scale; Hong Kong rice-paddy frog (Fejervarya multistriata) abundance was significantly positively related to farmland cover at the 1000 m scale; ornamented pygmy frog abundance was positively related to farmland cover at the 1000 m scale; and Beijing gold-striped pond frog abundance was significantly positively and negatively related to the landscape Shannon diversity index at the 1000 m scale and to water salinity, respectively. Amphibians quickly migrated and colonized coastal reclaimed land from older natural lands. However, two anuran species with specific habitat requirements tended to avoid areas with shorter reclamation histories. The single-species models revealed different responses to various land uses at the various scales, which indicated that land use management was important to amphibian conservation in coastal reclamation regions.

Ecology of Saline Watersheds: An Investigation of the Functional Communities and Drivers of Benthic Fauna in Typical Water Bodies of the Irtysh River Basin

In this study, we investigated how changes in salinity affect biodiversity and function in 11 typical water bodies in the Altai region. The salinity of the freshwater bodies ranged from 0 to 5, the brackish water salinities ranged from 5 to 20, and the hypersaline environments had salinities > 20. We identified 11 orders, 34 families, and 55 genera in 3061 benthic samples and classified them into 10 traits and 32 categories. Subsequently, we conducted Mantel tests and canonical correlation analysis (CCA) and calculated biodiversity and functional diversity indices for each sampling site. The results indicated that biodiversity and the proportion of functional traits were greater in freshwater environments than in saline environments and decreased gradually with increasing salinity. Noticeable shifts in species distribution were observed in high-salinity environments and were accompanied by specific functional traits such as swimming ability, smaller body sizes, and air-breathing adaptations. The diversity indices revealed that the species were more evenly distributed in high-diversity environments under the influence of salinity. In contrast, in high-salinity environments, only a few species dominated. The results suggested that increasing salinity accelerated the evolution of benthic communities, leading to reduced species diversity and functional homogenization. We recommend enhancing the monitoring of saline water resources and implementing sustainable water resource management to mitigate the impact of salinity stress on aquatic communities in response to climate-induced soil and water salinization.

From the Field to the Lab: Physiological and Behavioural Consequences of Environmental Salinity in a Coastal Frog

Environmental salinization is recognized as a global threat affecting biodiversity, particularly in coastal ecosystems (affected by sea level rise and increased frequency and severity of storms), and the consequent osmoregulatory challenges can negatively affect wildlife. In order to assess whether coastal species can respond to changes in environmental salinity, it remains essential to investigate the consequences of exposure to salinity in an environmentally-relevant context. In this study, we assessed the consequences of exposure to environmental salinity in coastal frogs (Pelophylax sp., N = 156) both in the field and experimentally, using a comprehensive combination of markers of physiology, behaviour and ecology. Exposure to salinity in the field negatively affected physiological parameters (osmolality, monocytes and eosinophils counts), as well as body condition and locomotor performance, and influenced size- and sex-specific habitat selection. Further, we demonstrated in a controlled experiment that short-term exposure to salinity strongly affected physiological parameters (salt influxes, water effluxes, immunity-related stress markers) and locomotor performance. Most of these effects were transient (water and salt fluxes, locomotor performance) once optimal conditions resumed (i.e., freshwater). Taken together, our results highlight the need to investigate whether exposure to environmental salinity can ultimately affect individual fitness and population persistence across taxa.